Calibration generator

1107calibration generator A calibration generator is of par- ticular use with many older gener- ation receivers, which have no, or a poor, frequency read-out. However, beat. the RF section of these receivers is invariably far superior to that of most modern models, and consequently The circuit is usable up to 30 MHz when CMOS devices are used, and up to around 300 MHz with HCMOS there are still many of these "oldies" in use. The circuit in the accompanying Z. R1 diagram provides calibration signals at multiples of 100 kHz and 1 MHz, all of which are available simul- taneously, so that no switching is necessary. The output signal of the crystal oscil- lator, Ti, is divided by 10 in ICI. Astable NI operates at a frequency CEB of around 22 Hz, which is low enough to allow zero beat tuning even in SSB operation. The 100 kHz harmonics sound (on AM) like a sort of wood- 4 L11f C3 pecker. 60P 1 Astable N3 operates at about 1.5 kHz and is gated with the 22 Hz signal. Consequently, the 1 M...